Neural indices of phonological and acoustic-phonetic perception

Neural discriminative responses index acoustic-phonetic and phonological differences. This study examined how contextual complexity modulates neural discrimination of speech sounds. The neural discrimination of Japanese /ma/ and /na/ was examined in a single-standard versus multi-standard oddball paradigm. In each paradigm, there were within-phoneme and cross-phoneme conditions. The results demonstrated that the single-standard cross-phoneme condition (single-standard [ma] vs. deviant [na]) elicited the largest mismatch negativity (MMN), followed by the single-standard within-phoneme condition (single-standard [na] vs. deviant [na]), and then the multi-standard cross-phoneme condition (multi-standard [ma] vs. deviant [na]). The multi-standard cross-phoneme condition elicited a late discriminative negativity (LDN) unlike the single-standard cross-phoneme condition. The later timing of the effect in the multi-standard condition suggests that task influences processing at the level of the MMN and LDN. Future studies are needed to further determine how the magnitude of varying factors, such as speech voice, influences phonological processing.